Named By: Mike P. Taylor & Darren Naish - 2007.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Sauropoda.
Species: X. proneneukos (type).
Size: Highly uncertain given the lack of fossil remains, but estimates exist depending upon what type of sauropod Xenoposeidon was. About 15 meters long if built like a brachiosaurid, alternatively 20 meters long if built like a diplodocid.
Known locations: England, East Sussex - Hastings Bed Formation, Ashdown Beds Formation?
Time period: Berriasian of the Cretaceous.
Fossil representation: Partial posterior portion of a dorsal (back) vertebra.
back during the 1890s, a fossil collector named Phillip James
Rufford discovered a partial dorsal vertebrae near Hastings in East
Sussex, England. Eventually catalogued as BMNH R2095, the
vertebrae was first thought to belong the genus Cetiosaurus
Lydekker, before eventually becoming Pelorosaurus
was about it for well over a hundred years as the specimen lay in
storage at the British Natural History Museum in London, England,
until one day a palaeontologist named Mike Taylor realised that this
partial vertebrae was quite unusual. Mike Taylor teamed up with
another palaeontologist named Darren Naish, and in 2007 a
description of this vertebra was not only published, but the
vertebrae became the holotype for a new genus of sauropod
The vertebrae though incomplete, displays a number of features that have simply not been seen upon any other sauropod dinosaur, which actually would make further remains attributable to Xenoposeidon as long as vertebrae were with them for comparison. The unfortunate thing about the vertebrae however is that although we know it belonged to a sauropod dinosaur, we don’t specifically know what kind. Fortunately in their 2007 description Taylor and Naish considered that Xenoposeidon may have been built either like brachiosaurids (similar to Brachiosaurus) or diplodocids (similar to Diplodocus). If brachiosaurid, then the length may have been about fifteen meters, but heavily built, while if diplodocid about twenty meters but lightly built. Unfortunately it seems that the only we anyone can be more certain about this is if more fossils can be found. Later analysis by Taylor however, leans more towards Xenoposeidon being a rebacchisaurid sauropod.
- An unusual new neosauropod dinosaur from the Lower Cretaceous Hastings Beds Group of East Sussex, England. - Palaeontology 50(6):1547-1564. - Mike P. Taylor & Darren Naish - 2007.
- Xenoposeidon is the earliest known rebbachisaurid sauropod dinosaur. PeerJ 6:e5212 - M. P. Taylor - 2018.